Improved PK of PEGylated FVIII in mice and rabbits. (A) HemA mice received 100 to 200 IU/kg BDD-FVIII, 30-kDa PEG-K1804C, 60-kDa PEG-F129C, 60-kDa diPEG-L491C/K1804C, or 60-kDa diPEG-F129C/K1804C. Citrated blood was collected at 5 minutes and 4, 8, 16, 24, 32, and 48 hours after tail vein injection. Plasma FVIII activities were measured by Coatest. Results presented are the percentage of recovery of FVIII activity in plasma after normalization with the input dose as mean ± SEM from 5 mice in each treatment group at each time point. (B) New Zealand white rabbits were dosed with 100 IU/kg full-length rFVIII, 60-kDa PEG-K1804C, 60-kDa PEG-F129C, or 60-kDa diPEG-L491C/K1804C. Citrated blood was collected at 5 minutes and 1, 4, 8, 16, 24, and 32 hours after injection. Plasma FVIII activities were determined by Coatest after R8B12 mAb capture. Results presented are mean ± SEM from 5 rabbits/treatment at each time point. (C) VWF KO mice were dosed with 250 IU/kg BDD-FVIII, 60-kDa PEG-K1804C, or 60-kDa diPEG-L491C/K1804C. Citrated blood was collected at 5, 15, and 30 minutes and 1, 2, 4, 6, and 8 hours from BDD-FVIII–treated mice or at 5 minutes and 4, 8, 16, 24, 32, and 48 hours from PEG-FVIII–treated mice. Plasma FVIII activities were determined by Coatest after R8B12 mAb capture. Results presented are mean ± SEM from 5 mice/treatment at each time point. The decay curves were fit with a noncompartmental model in WinNonLin.